test: add unit tests for get_external_class_inits

Tests cover: extracting __init__ from site-packages classes (click.Option),
skipping project classes, non-classes, already-defined classes, builtins,
classes with trivial object.__init__, and empty import scenarios.

tests/test_code_context_extractor.py

@@ -15,6 +15,7 @@ from codeflash.context.code_context_extractor import (
     extract_imports_for_class,
     get_code_optimization_context,
     get_external_base_class_inits,
+    get_external_class_inits,
     get_imported_class_definitions,
 )
 from codeflash.discovery.functions_to_optimize import FunctionToOptimize
@@ -4620,3 +4621,134 @@ class MyClass:
     # counter should be in context since __init__ uses it
     read_writable = code_ctx.read_writable_code.markdown
     assert "counter" in read_writable
+
+
+def test_get_external_class_inits_extracts_click_option(tmp_path: Path) -> None:
+    """Extracts __init__ from click.Option when directly imported."""
+    code = """from click import Option
+
+def my_func(opt: Option) -> None:
+    pass
+"""
+    code_path = tmp_path / "myfunc.py"
+    code_path.write_text(code, encoding="utf-8")
+
+    context = CodeStringsMarkdown(code_strings=[CodeString(code=code, file_path=code_path)])
+    result = get_external_class_inits(context, tmp_path)
+
+    assert len(result.code_strings) == 1
+    code_string = result.code_strings[0]
+    assert "class Option:" in code_string.code
+    assert "def __init__" in code_string.code
+    assert "click" in code_string.file_path.as_posix()
+
+
+def test_get_external_class_inits_skips_project_classes(tmp_path: Path) -> None:
+    """Returns empty when imported class is from the project, not external."""
+    # Create a project module with a class
+    (tmp_path / "mymodule.py").write_text("class ProjectClass:\n    pass\n", encoding="utf-8")
+
+    code = """from mymodule import ProjectClass
+
+def my_func(obj: ProjectClass) -> None:
+    pass
+"""
+    code_path = tmp_path / "myfunc.py"
+    code_path.write_text(code, encoding="utf-8")
+
+    context = CodeStringsMarkdown(code_strings=[CodeString(code=code, file_path=code_path)])
+    result = get_external_class_inits(context, tmp_path)
+
+    assert result.code_strings == []
+
+
+def test_get_external_class_inits_skips_non_classes(tmp_path: Path) -> None:
+    """Returns empty when imported name is a function, not a class."""
+    code = """from collections import OrderedDict
+from os.path import join
+
+def my_func() -> None:
+    pass
+"""
+    code_path = tmp_path / "myfunc.py"
+    code_path.write_text(code, encoding="utf-8")
+
+    context = CodeStringsMarkdown(code_strings=[CodeString(code=code, file_path=code_path)])
+    result = get_external_class_inits(context, tmp_path)
+
+    # join is a function, not a class — should be skipped
+    # OrderedDict is a class and should be included
+    class_names = [cs.code.split("\n")[0] for cs in result.code_strings]
+    assert not any("join" in name for name in class_names)
+
+
+def test_get_external_class_inits_skips_already_defined_classes(tmp_path: Path) -> None:
+    """Skips classes already defined in the context (e.g., added by get_imported_class_definitions)."""
+    code = """from collections import UserDict
+
+class UserDict:
+    def __init__(self):
+        pass
+
+def my_func(d: UserDict) -> None:
+    pass
+"""
+    code_path = tmp_path / "myfunc.py"
+    code_path.write_text(code, encoding="utf-8")
+
+    context = CodeStringsMarkdown(code_strings=[CodeString(code=code, file_path=code_path)])
+    result = get_external_class_inits(context, tmp_path)
+
+    # UserDict is already defined in the context, so it should be skipped
+    assert result.code_strings == []
+
+
+def test_get_external_class_inits_skips_builtins(tmp_path: Path) -> None:
+    """Returns empty for builtin classes like list/dict that have no inspectable source."""
+    code = """x: list = []
+y: dict = {}
+
+def my_func() -> None:
+    pass
+"""
+    code_path = tmp_path / "myfunc.py"
+    code_path.write_text(code, encoding="utf-8")
+
+    context = CodeStringsMarkdown(code_strings=[CodeString(code=code, file_path=code_path)])
+    result = get_external_class_inits(context, tmp_path)
+
+    assert result.code_strings == []
+
+
+def test_get_external_class_inits_skips_object_init(tmp_path: Path) -> None:
+    """Skips classes whose __init__ is just object.__init__ (trivial)."""
+    # enum.Enum has a metaclass-based __init__, but individual enum members
+    # effectively use object.__init__. Use a class we know has object.__init__.
+    code = """from xml.etree.ElementTree import QName
+
+def my_func(q: QName) -> None:
+    pass
+"""
+    code_path = tmp_path / "myfunc.py"
+    code_path.write_text(code, encoding="utf-8")
+
+    context = CodeStringsMarkdown(code_strings=[CodeString(code=code, file_path=code_path)])
+    result = get_external_class_inits(context, tmp_path)
+
+    # QName has its own __init__, so it should be included if it's in site-packages.
+    # But since it's stdlib (not site-packages), it should be skipped.
+    assert result.code_strings == []
+
+
+def test_get_external_class_inits_empty_when_no_imports(tmp_path: Path) -> None:
+    """Returns empty when there are no from-imports."""
+    code = """def my_func() -> None:
+    pass
+"""
+    code_path = tmp_path / "myfunc.py"
+    code_path.write_text(code, encoding="utf-8")
+
+    context = CodeStringsMarkdown(code_strings=[CodeString(code=code, file_path=code_path)])
+    result = get_external_class_inits(context, tmp_path)
+
+    assert result.code_strings == []